Apple Pencil 2nd generation won’t connect to iPad Pro 12inch

First, compatibility: Here is the full compatibility list for Apple Pencil. You’ll see that the first generation Apple Pencil is used with iPads that use a Lightning connector. Only the 2018/2020 iPad Pro - or the newest fourth generation iPad Air use the second generation Pencil:

Apple Pencil (2nd generation)

You can use Apple Pencil (2nd generation) with these iPad models: 

• iPad Air (4th generation)
• iPad Pro 12.9-inch (3rd generation) and later
• iPad Pro 11-inch (1st generation) and later

Apple Pencil (1st generation)

You can use Apple Pencil (1st generation) with these iPad models:

• iPad (8th generation)
• iPad mini (5th generation)
• iPad (7th generation)
• iPad (6th generation)
• iPad Air (3rd generation)
• iPad Pro 12.9-inch (1st or 2nd generation)
• iPad Pro 10.5-inch
• iPad Pro 9.7-inch

Not sure which iPad you have? Identify your iPad model.

Next, Apple’s guide for pairing and using the Apple Pencil:

Connect Apple Pencil with your iPad - Apple Support

If still having difficulties, here is one of the better troubleshooting guides for the Apple Pencil that may be helpful in working through common issues:

https://appletoolbox.com/apple-pencil-not-working-heres-our-troubleshooting-guide/

If you have checked through potential issues using the linked troubleshooting guide, then your Apple Pencil may be displaying symptoms of a dead battery - that will not accept or hold any charge.

Assuming that you do not have any other iPad charging issues - and that the Lightning Port of your iPad is free from debris - whilst the Pencil is plugged-in to the Lightning Port of your iPad, verify that the Pencil is recognised. If using a second generation Pencil with a compatible model of iPad, ensure the Pencil is docked:

Settings > General > About

Scroll to the bottom of the page - and you should find entries for the Pencil (iPadOS13 and earlier: one each for the physical and Bluetooth connections. iPadOS14 and second generation Pencil: only one entry). Finding these listed entries suggests that the Pencil electronics are good - otherwise, you have a totally dead pencil.

Check the Battery Widget for the charge status of the Pencil. Is it 100%? If not, let the Pencil charge; if it is fully charged, disconnect from the iPad. 

When disconnected from iPad, does the Pencil disappear from the Battery Widget - or it’s indicated state of charge suddenly fall? If either of these are true, then the Pencil battery is likely to be failing or dead.

The tiny internal Li-ion battery is susceptible to permanent/irreversible damage through being left discharged for long periods. Even some “new” pencils can exhibit signs of failure out-of-the-box if they are “old stock”. It is essential that if you have an Apple Pencil that you charge it regularly - whether used or not - so as to protect the battery from deep-discharge. Do not allow a pencil to remain in low-charge state for any period of time - as the internal battery will fail, rendering the Pencil useless. Setting aside an unused Pencil, for extended periods, is a recipe for premature death of the Pencil battery. A second generation Pencil should always be docked with the iPad whenever it is not being used.

If the Pencil Battery has failed, the only remedy is to replace the Pencil. If the battery has failed and your pencil is within its one-year warranty, you should look to having it replaced by your retailer or at an Apple Store.

I hope this information proves to be helpful in both diagnosing and resolving the problem.